Door check and the like



July 8, 1952 J. G. KNIFE DOOR CHECK AND THE LIKE 2 SHEETS- SHEET 1 Filed Aug. I8, 1950 2 a g y f a INVENTOR Jam es .fnz/ve ATTORNEY July 8, 1952 J. G. KNIFE DOOR CHECK AND THE LIKE 2 SHEETS- SHEET 2 Filed Aug. I8, 1950 INVENTOR Jal/*ns G. /n z/'oe ATTORNEY Patented July 8, 1952 g UNITED srArss- I,20 Claims.

This invention relates to door checks and the like; and it consists of a device suitable for use asa door check or the like comprising an assembly of tclescoping rigid' tubes closed off at theends by end plates forming air tight seals, a concentric resilient tube mounted outside the rigid tubes, said resilient tube coveringthe joints between said telescoping rigid tubes, whereby the assembly as a whole forms a bellows, and venting means permitting the passage of a minute ow of air into and vout of said bellows; said resilient tube being-mounted so that, when .the assembly of rigid tubes is extended uponopening of the door, the resilient tube hugs the rigid y tube assembly, whereby a delay is caused before the door starts to close; all as more fully hereinafter set forth and as claimed.

Objects of the present invention are to irnprove and simplify present door devices, to lessen the cost of present door checking devices and to simplify the construction of same, and *specically to provide in one device means for holding a door open and stationaryv for an adjustable period 'of time, for automatically closing said door at the end of such time and for causing the door to shut quickly but quietly. 5

Other objects of the present invention are to provide a unit which may be easily and cheaply attached to doors'inoices, libraries, homes, hospitals and other institutions for the convenience and safety of the personnel afforded bythe device, to provide a device which lwill preventinjuries and falls due to hitting or beingk tripped by aclosing door. to provide by thisV device'a means to hold a door open and stationary so a person with both arms occupied or 'lled may by bodily contact, as by pushing with a foot,` open the door and pass through without having said door swing back and hit him or in any way affect him, and to have a unit which is suficiently cheap to enable use on numerous doors of institutions.

A large number of different types of door checks have been developed and put to use. Some of these merely prevent thev door from slamming when it closes While others close the door both slowly and positively. -But in the case of many doors, such as those in restaurants, railway stations and hospitals it would be advantageous if. after opening, they would remain in open position for a relatively short period before they start to close. To my knowledge no simple and practical door check has been developed heretofore which is capable of producing this desired delaying eect followed by automatic closing oi the door. l

havediscovered that it is possible to produce a delay" of the type described" by a doorv check which makes practical use of the fact that, when a resilient tube is stretched, its diameter becomes reduced so that it will grip or hug a concentric inner tubey over which it iits closely, but not tightly, when in unstretched condition. rThis hugging action continues for a short period even after tension on the resilient tube has been relaxed. The hugging action can be increased, prolong@1 and/or controlled .in'its time'period by the use oi a vacuum inside the resilient tube.` Forex- `ample, I have discovered that the hugging action will continue after tension on the resilient tube has relaxed as long as a vacuumis maintained inside the tube assembly.' lf a controlled air leak is provided 'which will permit a minute flow of Vair vinto the assembly an accurate controlen the time period of the hugging is obtained.

I make practical use of these phenomena in my door check which comprises an assembly of rigid telescoping tubes closedy oi air tight at their outer ends and an outer resilienttube extending over the joints between the rigid tubes and secured thereto :by air tight joints in such fashion that the assembly of tubes as a whole forms in effect a bellows in which a'partial vacuum can be produced by extending the device and a lpressure'by compressing it. f A small controlled leak-- age of air into and out of the bellows is advantageous and this can be accomplished byhaving anair vent vand lmeans for'controlling the iiow of air through the vent.

The desired gripping or hugging action which produces the desired delay before the door starts tov close may be effected (l) by the stretching of the resilient tube alone, (2) by the vacuum produced inside the assembly of tubes or (3) by a combination of the stretching eiiect and the vacuum effect. lf stretching of the resilient tube is relied upon to produce the hugging effect it is essential, of course, for this tube to be secured to the rigid tubes by tight joints so the resilient tube will be stretched when the assembly of tubes is extended. l'When the resilient tube is thus stretched it tends to pull the assembly back into yits compressed position-and hence it isusually age of air into the assembly is necessary in order fect since, if this is done the length...of.the..delay.

prior to closure of the door can be closely controlled by control of the quantity ofjaiizpassing;,y through the air vent. Whenlhoth efectsrare. utilized it is necessary, of course; to secure-the ends of the resilient tube tightly to 'the, .rigidz.

tubes beneath, so the resilient tube is stretched,

andalsoto employ meansiorregulating the .quantityof air admitted. .throughthe -.air vent.

The-.resilient tube used on .my door .l check .can be `.astraight rubber tubeinthe cheaper embodiments but itis more. .advantageous gto. ,employ an accordion.- plaited tube. This.- reduces the .friction in. thedevice. Both. types .of vresilient vtubes can.l be tapered if .desired sotheir vends t the rigid. tubes closely. To .make.. tight A.joints between. .the resilient. tube andthe rigid tubes... .any suitable .plastic rubber cement caribe .used,.which. iscapableofforming a. tight joint betweenmetal and rubber. If...desired. it is. .possible,.of course, to rivet the-ends .ofthe resilient tube to: therigid metal .tubes in` which case thecement. used ,has the primary purpose of. making .the .joint air tight.

My invention .can be .explainedingreaterde- .tail .byreierence Ato .the .accompanying drawings whichy show, .more .or less .diagrammatically,v four .embodiments of my ,doorcheck.. In this showing, Fig.. 1 .is .anelevationof my bellows type .door check...

Fig..2 an .endview oi .thebellows type check. taken from the left. hand. end .of Fg.,1,

Figf3 .fis a longitudinal section .of .thesamedevice, taken .alongthe line....3.3..of Fig.v 2 :and shown in vcompressed position,

Fg.- 4..is Yasimilar View. ofthe; bellows type checkin-extendedposition, Fig.. 5 is -a .longitudinal section through a mod ieddoor check.

Fig.. -6 isV a longitudinal. section. through .a .sec-v ond modification,

Fig. 7 is a similar .view..throughra.thirdmodi- .catiort while Fig.; 8 is .a'vperspective -view of a bellows type check .secured Abetween thetop of ardoor frame andthe Vplate at the top of thefdoor.

Inv the yfvarious .views .like parts .are .designated by *1ikefreference'-numerals.` The bellows type `doorcheck shown Ain Figs.v 1, 23, 4 and.8 4.is formed with a rectangular .baseplate l torwhich a baseer outer tubel 2 is welded .or lotherwise secured so that .the plate-closes ,the end-of.l the r.tube

with anair'tight joint... A smaller inner Vtube 3 with ..the end platesJ and 4,-.and the elastic tube .5 .form in .eiect abellows which can be Vcompressed into the positions shown in Figs. l and 3 or expanded into the position shown in Fig. 4. A vent hole 8 is provided to provide a flow of air into and out of the bellows.

In my preferred embodiment, shown in Figs. 1, 2, 3, 4 and 8, means are provided for controlling the quantity of air passing through the vent hole, this means taking the form of a rubber or other 4'plastic .elastic tube Q .which isxslipped over thebase tube 2 and usually folded-over at one end as at l0. By folding this tube over to a greater or lesser extent the amount of air passing through the vent can be closely controlled.

For lproper operation of my door check it is essential-toghave a minute leakage of air through vent 8.in .order gradually to break the vacuum when the check is extended as shown in Fig. 4. For;this.;reason it is advantageous to employ a material which is slightly porous as well as elastic for `the sleeve 9, such` asfoam rubber, for example. .Asthe door closes any excess airin the bellows .can readily escape through .the vent 8.

.The .-end -plates l and 4 .can be used convenientlygas .means for securing Amy door check tothe doorand the .doorframeworln As shown inFigs. l,v 2,13, 4 .and 8 thesevplates-canv be .provided Vwith extensions .Il .providedwith holes `I2 for mounting. purposes. A convenient way ofmounting this type of door checkis shown in-Fig. 8. This iigure is a .perspective view .representing the top of a-door :13, hinged at the left to the door jamblll upon. hinges .l5 insuch manner that thedoor opens. outwardly. A .door checkof the bellows typeissecured-at its vbase end to theplate i6 ,at

' .thetop'of the door V.by means .of a staple l1 which passes through the hole 12in the end plate. l. At its other end the `door check is secured. in similar mannerto .the .doorframe bystaple i8 whichpasses through the .hole .I2 .in end .plate 4. .Thestaple I8 is conveniently positioned about .2 .inches inwardly from the ,door jamb and approximately 11/2 to 2.inches below the doorplate. The position of staple II depends,.of courseuponl the lengthxof the door checkfbut it can be conveniently placed about l to ZinChesinWardly from the door when .the latter is in its closed position. Thisgmounting is not conventional .but `is advantageous for myfdoor check vowing to the lfact thatr the-check' is .extended only from about .1.1/2 .to 2 .inches "whenthe door moves .from its `,closed position to its 90'open position, these figures applying: to acheck having an over-all length of about 9 inches and .having -a 5 inch bellows, whose'outer metal tube has va diameter of about 11A; inches and whose Iinner metal tube has a diameter of about 11/8 inches.

When a door check is mounted in conventional .fashion the extension required usually amounts fto from about '5 to 7 inches. An extensionof this ymagnitude requires a bellows having a length of approximately 8 inches or longerand, since the elastic bellows of my door check is the mostrexpensive element inthe device itis advantageousfto keep this as .short vas possible.

As :already mentioned .it is possible .to make vuse ofv thefreduction in diameter alone .toeiect a delayed-closing of a-door equipped with one of'my .door checks. Modications making use ofthis single -eiect are shown in Figs. 5 and 6. In the vmodification of Fig. 5a straight rubber tube A5a is used in place of the accordionplaited tube of the Vpreferred modication. And the vent l8rmay .be .fleft open. The telescoping tubes 2a and .3a. mayY be made of `considerably smaller diameter, if desired, the inner tube being fromabout J/2 vto 1 inch in outer diameter and the outer tube slightly larger to t. In this modification the tubes 2a and 3a. are closed off at their ends by means ofbutt hinges, shown generally at I9, having plates la, Ila andV 4a, Ila, respectively,

mounted on hinge Vpins 2t. Tube 2a is welded or soldered to the hinge plate la with an air tight joint while tube 3a is secured in similar manner to hinge plate 4a. The free hinge plates lla at either end are provided with-screw holes 12a, used in mounting the device. Rubber tube 5d is secured to tube 2d by an air tight joint 6 as in the modification of Fig. 1.

The modification of Fig. 5 can be mounted in conventional manner between the door jamb and the door frame by screws secured therein and passing through screw holes I2a. When a door equipped with the modification of Fig. 5 is opened, the tube 5a. stretches and is thereby caused tightly to hug the tube 3a. Air is drawn into the vent 8 so that the vacuum produced in the bellows is negligible unless the door is opened very quickly. However the friction of the tube 5a` against the tube 3a is sufficient to cause a delay in the closing of the door. Air escapesfrom the vent =8 during closing but the vent is suiiiciently small so that slamming of the door is prevented. v A further modification of my door check is shown in Fig. 6. In this modication the tube 2b can be made identical to the tube 2 of the modification shown in Figs. 1, 2, 3, 5 and '7. But the tube 3b is of the same size as 2b and is advantageously of about the same length. The smaller tube 2l fits inside tubes 2lb and 3b with a loose fit and may be sufliciently long to hold the rubber tube 5b slightly stretched even when the check is in its compressed position, at which time its ends bear against the plates i and li. In this modification the rubber tube 5 may be either accordion plaited or smooth, a smooth tube being shown in Fig. 6. This tube is secured by air tight joints and 'l to tubes 2b and 3b, respectively, preferably by a cement. A spring 22 can be mounted inside tube 2l, as shown, being fastened at its ends to end plates l and 4. If desired a similar spring may be used in the other modifications of my door check. It serves to supplement the action of the rubber tube in making the door close tightly. Such a spring serves as a safety factor since, if the joint at 'l should become loose for any reason, the check will still operate satisfactorily owing to the action of the spring serving to closethe door; otherwise the checkr would be inoperative in closing the door. e

When a sliding fit is used at one end of the flexible tube it is necessary to employr ar spring to effect complete closing of the door. A modification of this type is shown in Fig. 7. This modification is exactly like that of Figs. 1, 2, 3, 4 and 8, except that the joint 'la at the' left end rof the accordion plaited tube 5c is a sliding joint which should nt closely but need not be air tight and that a spring 22 is provided to close the door. In the operation of this niodication, when the door is opened a vacuum is produced inside the tube assembly. The resilient tube 5c -is not stretched, in fact the length of this tube may be decreased slightly due to the eifect of the vacuum tending to reduce its length. But the vacuum causes the tube 5o to grip or hug the tube 3 which produces the desired delay before the door starts to 1 close. The vacuum also causes the sliding joint at la. to become substantially air tight. When the vacuum has been gradually dissipated by the slow leakage of air through the vent 8 and under the sleeve 9the gripping action stops and the spring 22 closes the door. The air which has leaked into the tube assembly becomes compressed and this prevents slamming of the door. But this air escapes rather'quickly since it raises the sleeve Il! which acts somewhat like a one-way valve. Hence the door closes rather quickly and slightly after the delay mentioned. In this as well as in the'modication of Figs. 1, 2, 3, 4 and 8 the delay produced prior to the closing of the door can be controlled by regulating the size of the vent 8 and the extent to which it is closed -by the tube 9. This delay can also be controlled conveniently by the person who opens the door since the further the door is opened the longer the delay produced before it starts to close. This is a unique and inherent feature of my door check. 1 e

In order to insure complete closing of a door to which one of my devices is attached in which no auxiliary spring is employed, the resilient tube 5 should be under a slight tension even when the device isin its compressed position. This tube should be sufficiently rigidso that it does not buckle when the door is closed yet sufficiently elastic to stretch at least from about 11/2 to 2 inches when the'door is opened. My tests show that a vulcanized natural rubber tube having a thickness of from about ss to sgg inch has the proper characteristics.

In one operating embodiment, of the type shown in Figs. l, 2 and 3, the tube is 5 inches long, having an inner diameter of 11A; inch, withl accordion plaits and the thickness of the rubber is 1/8 inch at the ends, where it is secured tothe metal tubes and als inch in between. This tube stretches from about 2 to 3 inches as the door is opened. yThis tube is sealed at one end to the inner end of an aluminum tube having a length of 5 inches, an outer diametervof 11A inches and a wall thickness of .058 inch, while the other end of the resilient tube is sealed close to the outer end of a smaller aluminum tube which telescopes the larger tube, said smaller tube having a length of 11 inches, an outer diameter of 11/8 inches and a wall thickness of v'0.046 inch. The clearance between two telescoping tubes of this type is advantageously from about 0.009 to 0.027 inch. It can be greater but preferably not over 0.060 inch. The air vent can be made with a diameter of from about /r to 1/8 inch. If uncovered it should be from about 1&4 to als inch in diameter depending upon the cubic volume of the door check.- 1

In the specific device described above the air vent was g1g inch in diameter and was covered by a rubber sleeve which substantially prevented the access of air during opening of the door. This device caused the door to hold'its open position for a period varying from about 5 to 15 seconds before it'started to close, Vdepending upon the extent to which the door' was originally opened. With the vent entirely uncovered the delay was reduced Ato about half of these figures.

While I have disclosed what I consider to be the best modifications of my door check it is evident, of course, that various modifications can be made in the specific structures'which have been described without departing from the purview of this invention. While I have described the rubber tube 5 as beingslightly tapered, it is possible, if the tube 2 is suiciently thin and if tube 3 makes a close sliding t withv this tube, to employ a straight rubber tube. The tube 5 is sufficiently resilient so that it can readily'be aeoaisi clamped; air tghtat.. 1.. If .tube. 5,. islmolded spe: cially.. the. end which. is. secured. to. tube, 3.A can be madeftd fit. this. tube. while the, other. end. can be made slightly: larger to, ntthe.. tube 2', the tube between.theseA ends being made without` a taper, The. tube .5 obviously can.. be made of any elastic.. plastic materialwhich. is. substantially. impervious. Natural; rubber or .any Otthesyn.-y thetic elastomer-s. can.beused,-,for example. Itis adyantageousfto employ an elastomer which. is resistant,towa1'ds oil,V such as.- neoprene,;since customer-s are likely .to putoil inthe venthole 8 thinking.. that my check operates. similar toconventional .door checksV which operate. with a plunger.. There is. aslight tendency for thetube Iii-to'- stick to the metal tube 3 whenthe check is its expanded positionrIfhis .tendency can be overcome by dusting the tube 3 or the inside.. of. tube 5 with graphite. or talc, forv example.. Asingle.-.application-. of. one .ofthese. materials. is usually.- suiiicienttov lastvindennitely if the.- rubber tube-isproperly made.

While I lia-ve described my device as being used primarily for a. door check it is.v evident that, it cart-bei made use of for any purpose in which it is desired to' produce a buffering or dash-pot efectwhila permitting a motion in one direction fora-.short distance followedby a delay and then aireturn motion; with. a buffering. effect. rIhus my device can be used as a dash pot or as. a re.- coi'Lmechanisnr .for a, gun or the like.

The tubes. used in my device are not, necessaril'ycylindrical.; a square or rectangular section can be used if desired. Cylindricaltubes are generally' cheaper and hence preferred for most purposes. My. device 'can be. made of. any size desired according to the: use to which itis put. The rigid; tubes can. be madeY of. metal, such. as aluminum; or'steel, and itlisalso possible: to, make these ofv any ofthe conventional` molded plastics, such; as: phenolf-formaldehyde resins, polymerized vinylresins; etc. The. air vent used in my device may: be. positioned atanyconvenient poi-nt on .the tube assemblyv and, or course, any conventional meanszcan be used. for controlling the rate of air'ow'therethrough. Further modications of my device whchlall Within the scope of the-following. -cl'aims will be. y immediately `evident to those skilled. in the art.

VWhatIclaimis.:

LA device suitable for. use as. a door check. to be. mounted; between: a door and its framework, comprising. an assembly of telescoping rigid tubes closed oli at; their outer ends by plates forming air tight'. seals, a closely litting concentric: resilient tubeymounted with substantial-lyv a-ir tig-ht joints. outside the: rigid tubes, saidresilient tube covering the. jointsa between said telscopingrigid tubes, whereby the assembly asa whole is substantially air tightand atleast a partial vacuum is. produced inside the assembly when it becomes extended as the. door is; opened,A saidvacuum causing said-resilienttube temporarily te hug. the rigid tubes whereby a delay is caused before the door: starts toclose, andv resilientrneans.v tending to .pullthe saidL assembly together. to close the door..

. 21;. The: device. of. claimV 1 wherein saidA resilient tube is. tightly secured. to two.r of. said rigid tubes whereby itis stretched as the door is opened, said resilient. tube comprising the; resilient.. means tending to close. the door.

3.. The device of cla-im 1 .wherein said. resilient tube` is. tightly secured. to. one.: of said. rigid tubes and` has. a sliding -t with. anothen a.` spring being S provided. to pull the assembly` of. tubes. together to|` close. the. door.

4.. The. device o--claimY 1. wherein said resilient tube is accordionplaited.

5. Thedevice-of claim. 1 wherein said-resilient tubeis tapered in order to nt the tube assembly closely.

6. The. device of claim 1 whereinl said resilient tube-is a. straight rubber tube.

7. The device of claim 1 wherein the assembly of rigidv tubes consists of. two. end tubes. of. the same. size closed ofi at their outer ends and a longer concentric inner tube, the resilient tube being mounted outside the inner tube-and tightly secured tothe. inner endsof. said end. tubes.

8. Ther device of. claim. 1 wherein the assembly of rigid tubes consists of two concentric tubesthe inner tube being longer than the outer tube, the said resilient tube being rigidly connected to. the inner end of the outer tube. and tothe inner. tube close to its end plate.

9.-. Thedevice of claim l wherein the assembly of rigid tubes consists of two tubes the inner tube being longer than. the outer tube, the said. resilienttubebeing rigidly secured to theinner end ofV the outer tube and having a sliding, substantially air tighty t on the inner tube.

10. Thev device of .claim 1 whereinv said end platesare provided with extensions formounting the check.

11. A device suitable for use asa door check to be mounted between a door and its framework, which. comprises a pair of. end plates adaptedl to be usedinthe mounting of the door check, apair of telescoping rigid tubes mounted.. between said end. plates and secured thereto with airv tight joints, the inner of said tubes being the longer, a closely-ntting accordion-plaited, resilient tube. secured with air tight joints at one of its endsf to the inner end of the outer rigid. tube and at. its other end to the inner rigid tube adjacent its; end plate, whereby the assembly as a whole forms a bellows, an air. vent. for controlling the amountof air passing into and out of said bellows, said as.- sembly being so constructed and arrangedY that, as the assembly is extended upon opening of the door, thev resilient tube becomes stretched so that it hugs theV said inner tube causing a delay in the. closing of the door.

12.. 'I'he device of claim 11v wherein means are provided to substantially prevent entrance of air through said vent into said bellows as the door. is opened; whereby the vacuum produced in the bel.- lows assists in causing the resilient tube to hug the rigid tube beneath.

13. The .device of claim ll wherein the air vent issufliciently large substantially to prevent the productionof a vacuum inside the bellows as the door is opened and the resilient tube is caused to hug the rigid tube beneath substantially solely due to its stretched condition.

14'. The device of claim 11 wherein said resilienttube is accordion. plaited.

l5. The device. of claim l1 wherein saidresilient tube is a straight tube.

16.. The device or claim 11 wherein said resilient tube is. tapered so that at its larger endit fits, the larger rigid tube and at its smaller end it fits theinner rigid tube.

17. A device suitable for use as a door check adapted tobe mounted between a door and its framework, which comprises a pair of end plates, a pair of rigid end tubes having the same diameter secured. to said end plates with air tight-joints, a closelyv tting, third. tube mounted; inside and4 between said end tubes'having a length greater than that of said end tubes, a resilient concentric tube tightly secured with air tight joints to the inner ends of said end tubes, the assembly as a whole forming a substantially air tight bellows, means for controlling the Aamount of air passing into and out of said bellows, the tubes being so constructed and arranged that when the end tubes are pulled apart upon the opening of the door the resilient tube is stretched and caused to hug the inner rigid tube whereby a delay is caused before the door starts to close.

18. A device suitable for use as a door check to be mounted between a door and its framework, which comprises an assembly of telescoping rigid tubes closed off at their outer ends by end plates forming air tight seals, a concentric resilient tube mounted with air tight joints outside the rigid tubes, said resilient tube covering the joints between said telescoping rigid tubes, whereby the assembly as a whole forms a bellows, venting means permitting the passage of a minute flow of air into and out of said bellows, said resilient tube closely tting the rigid tubes whereby, when the assembly of tubes is extended upon opening of 10 the door, the resilient tube hugs the rigid tube assembly, whereby a delay is caused before the door starts to close.

19. The device of claim 18 wherein said resilient tube is tightly secured to the rigid tubes so that it is stretched when the door is opened and this tube is thereby caused to hug the rigid tubes.

20. The device of claim 19 wherein said resilient tube is tightly secured at one end to one of the rigid tubes While a sliding joint is provided at its other end so that the vacuum produced upon opening the door causes the tube to hug the rigid tubes.

JAMES G. KNIPE.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date 1,602,379 Kraft Oct. 5, 1926 FOREIGN PATENTS Number Country Date 259,603 Great Britain June 2, 1927 

